1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a stereoscopic display which switches between a two-dimensional (2D) mode and a three-dimensional (3D) mode and a method of thereof, and more particularly, to a stereoscopic display which switches between a 2D mode and a 3D mode using two polarization grating screens and a method thereof.
2. Description of the Related Art
In general, a 3D image is made based on the principle of stereo image sensing by two eyes. Binocular parallax occurring due to two eyes separated about 65 mm from each other is the most important factor for producing a 3D effect. Recently, the demand for stereoscopic displays that provide a stereoscopic image using binocular parallax has greatly increased in various fields, such as medical applications, games, advertisement, education applications, and military training. With the development of high resolution televisions, stereoscopic televisions providing stereoscopic images are expected to be widely used in the future.
Stereoscopic displays are divided into displays for use with glasses and glassesless displays. In general, as shown in FIG. 1A, a stereoscopic display for use with glasses 120 includes a liquid crystal display (LCD) 100 which displays an image with a predetermined polarization component, a micro polarizing screen 110 which changes the direction of polarization of an image for a left eye and an image for a right eye produced by the LCD 100, and polarization glasses 120 which transmits images with different polarization states for the left eye and for the right eye. For example, the micro polarizing screen 110 is a combination of 0° retarders 110a and 90° retarders 110b that are alternately interspersed. Also, the polarization glasses 120 include a pair of polarization plates 120a and 120b through which light with different polarization states is transmitted. Since the micro polarizing screen 110 makes the directions of polarization of the left-eye image and the right-eye image different from each other, and the polarization glasses 120a and 120b respectively transmit the left-eye image and the right-eye image, a viewer can see a 3D image.
However, the above-mentioned stereoscopic display has a disadvantage in that the viewer must wear the polarization glasses 120 to see the 3D image. To solve this problem, a glassesless stereoscopic display has been developed. The glassesless stereoscopic display produces a 3D image by separating an image for a left eye from an image for a right eye without the use of glasses. In general, glassesless stereoscopic displays are divided into parallax barrier displays and lenticular displays.
In a parallax barrier display, images to be seen by left and right eyes are displayed in an alternate vertical pattern and portions of the pattern are blocked by a very thin vertical lattice, that is, a barrier. In this way, a vertical pattern image to be seen by the left eye and a vertical pattern image to be seen by the right eye are separated by the barrier and the left and right eyes see images at different viewpoints so as to combine to form a 3D image. According to the parallax barrier display, as shown in FIG. 1B, a parallax barrier 50 having apertures 55 and masks 57 formed in a vertical grating pattern is disposed in front of an LCD panel 53 that has left-eye image pixels L and right-eye image pixels R respectively corresponding to a viewer's left eye LE and right eye RE, such that each eye sees a different image through the apertures 55 of the parallax barrier 50. The left-eye image pixels L output light to be input to the left eye, the right-eye image pixels R output light to be input to the right eye, and those pixels are alternately formed in a horizontal direction in the LCD panel 53.
Meanwhile, to provide a 2D image or a 3D image according to an image signal displayed on the display device, the stereoscopic display must switch between a 2D mode and a 3D mode. To this end, a variety of switchable stereoscopic displays have been developed. For example, according to a stereoscopic display disclosed in U.S. Patent Publication No. 2004-0109115, two micro retarders including a plurality of vertical stripes are moved relative to one another such that a 2D image is realized by transmitting all images and a 3D image is realized by forming a non-transmissive vertical parallax barrier.
However, since the apertures through which an image is provided are densely aligned in a vertical direction, the parallax barrier display has drawbacks in that a 3D image has a low resolution and color and brightness vary according to a viewer's position.